Printing plate clamp



1944- H. M. BARBER PRINTING PLATE CLAMP Filed Oct. 2, 1942 2 Sheets-Sheet 1 r m2 xmulu Vii Aug. 8,1944. H. M. BARBER PRINTING PLATE CLAMP Filed Oct. 2, 1942 2 Sheets-Sheet 2 IN V EN TOR.

Patented Aug. 8, 1944 UNITED STATES PATENT OFFICE Howard M. Barber, -Pawcatuck, Conn., assignor to C. B.;Cottrell "8.; Sons Company, Westerly, R. I., a corporation of Delaware Application October 2, 1942, Serial'No. 460,501 v 7 Claims. I o1.1o1-3s7) In the'use of printing plate-clamps of the type where 'a'screw is employed for clamping the cyl inder and nutto the plate support, 'as, for instance, a cylinder, in their plate clamping position along a groove in the cylinder, it has been found that at high speeds it'is difiicultto maintain'these clampsin their'operative positions due to the strain of holding the plates on the cylinder at said high speeds. It has also been found that the clamps not only break due to the excessive strain thereon under high speeds but that they also break due to the fact that the clamp screws receive directly the shocks of the blows delivered by the pressmen against the nuts to force the clamps along the grooves into their plate clamping positions, thus causing a shear ing strain on the clamp screws.

'Theobject of my invention is toprovide means for relieving this shearing or side strain 'on the clamp screws when forcing the clamps into their operative position, and thus make it possible to succ'cessfully use this type of clamp in high speed presses; said strain on the screws being eliminated by the provision of 'coacting surfaces of various forms between the'plate hooks and nuts, for absorbing the blows on the nuts and thus preventing the effect of the blowsbeing transferred to the clamp screws. I

Practical "embodiments 'offmy invention are represented on an enlarged scale in the accompanying drawings in which Fig. 1 represents a detail side view of a grooved cylinder with one form of printing plate clamp engaging one curved side edge of the printing plate;

Fig.2 represents a section'taken in the plane of 'the line II- -II of Fig. 1:

Fig. 3 represents a section taken in the plane of'the line III-III of Fig. 2;

Fig. 4 represents an end view of nut;

Fig. 5 represents a bottom plate clamp hook;

Fig. 6 represents an and g 1 Fig.7 represents a side view of the hook.

the plate clamp plan view of the end view of the hook;

Fig. 8 represents a section similar to Fig. 3,

showing asecond form of clamp;

Fig. 9 represents a view of the nut; Fig."1'0 represents an end view of the same; Fig. 11 representsabottom plan view of the hook; Fig. 12 represents an end view of thesame; and

Fig; 1'3'r'epresents a side view of the hook.

'-Fig.f14 represents a section similar "to Fig. '3', showing a third form of clamp;

Fig. 15 represents a side viewoi the nut;

Fig. 16 represents an end view of the same;

Fig. 17 represents a bottom plan view of the hook;

Fig.

and Fig. 19 represents aside view of the hook. Fig. '20 represents a view similar toFigJl, showf ing the form of clamp illustrated in Figs. lite 1.9 inclusiveyin which the hook is flat instead "of curved, rendering 'it adaptable for engaging 'a straight edge of, the curvediprinting plate;

Fig. 21 represents'a bottom plan View of the hook;'and

Fig. 22' represents aside view of the same.

Fig. 23 represents adetail'sideview' of a grooved cylinder with a fourth form of clamp in which the hook is curved for engaging a curved side edge of the printing 'plate;

Fig. 24 represents a section taken in the o'fthe lineiXXIV-XXIV of'Fig. 23; V

Fig. 25 represents 'a'sectiontak'en in thepl'ane *18 represents an end 'view of the sarnei plane of the line XXVXXV of Fig. 24; I

Fig. 26 represents an end view of theplate clamp nut;

Fig. 27 represents .a bottom plan view of the plate clamp hook;

Fig. 28 represents an end view of the same; Fig. 29prepresents a side View of ,the hook; and Fig. 39 represents a side view of the hookin its 'fiat formfor'eng'agement with a'stra'ight edge of the'printin'g plate. a v 'The printing plate support "which is v.herein shown as 'a cylinder, is denoted by], and .one of its usual-spiral grooves by 2, which groove may. be of any well known or approved cross sectional shape.

The curved printing plate vis denoted by ;3,' one of its curved beveled edges by 4 and one: of its straight beveled edges by 5.

The plate clamp comprises the nu't't, the

hook! and theclampscrew 8. In the embodi ments shownin Figs, '1 to 22 inclusive the plate hook 1 'is'shown'a's provided with a guide mem;

her 9 which is provided with parallelside edges 1 1,10, slidably engaging theside walls of the either-the curved "edge 4 or the straig'htedg'e -5' of "the printing ,plate 3, as the 'case may be. It

will be noted that the guide member; :9 projects This nut 6 in all of the embodiments illustrated is shown as having a shallow recess ll adapted to receiv the guide member 9 of the plate hook I when the parts of the clamp are assembled.

Coacting surfaces are provided on the plate hook guide member 9 and the nut 6 for preventing the plate hook from exerting a side strain on the clamp screw 8 when endwise force such as repeated blows is directed against the clamp nut 6 to drive the clamp along the cylinder groove into engagement with the curved or straight beveled edge of the printing plate 3.

In the embodiment shown in Figs. 1 to 7 inclusive the uprising inner wall of the shallow recess H in the nut 6, which houses the guide member 9 of the plate hook I, is shaped to form two angular surfaces [2, I3 which coact with corresponding angular surfaces l4, [5 of the adjacent end wall of the said guide member; the coacting surfaces l2 and I4 being parallel with the back edge of the plate h'ookand the coacting surfaces 13 and I5 being at right angles to the cylinder groove 2.

In the embodiment shown in Figs. 8 to 13. inclusive the uprising inner wall of the shallow recess ll, in the nut 6 forms a plane surface I6 which coacts with a corresponding plane surface on the hook guide member 9.

In the embodiment shown in Figs. 14 to 19 inclusive the uprising inner wall of th shallow recess II in the nut 6 has a curved surface I! which coacts with a' corresponding curved surface 18 at the adjacent end of the guide member 9,

said curved surfaces being concentric with the clamp screw 8 so that the hook may properly seat against the edge of the printing plate even though the spiral groove 2 in the cylinder is not milled at exactly forty-five degrees. In the embodiment shown in Figs. 20 to 22 inclusive the plate hook is shown as straight instead of slightly curved so as to facilitate the clamping of the straight beveled edge 5 of the plate lengthwise, of the cylinder. ures' 20 to 22 inclusive the coacting surfaces are of the form illustrated in Figs. 14 to 19 inclusive.

In the embodiment shown in Figs. 23 to 29 inclusive the nut 6 is shown as having a circular recess l9 concentric to the' clamp screw 8 for snugly receiving the circular concentric guide member 20 of the curved hook 1, thereby permitting the hook to be rotatedon the nut to engageeither one of the opposite curved. edges 4 of the curved plate 3. It is understood that the side walls of the recess and'guide member form the coacting surfaces which prevent the shock of the blows on the nut 6 being transmitted to the clamp screw 8. In Fig. 30' the plate hook I is shown as flat for engaging one of the straight edges 5 of the printing plate 3.

In all of the embodiments the coacting surfaces of the'plate hook and nut are so located that they, rather than the clamp screws, will receive the force of any blows against the nuts for driving the clamps into their engagement with the printing plates. I 1

In these Fig While I have shown the printing plate clamps as mounted on a cylindrical support, it is obvious that these clamps could be readily adapted without invention for use on flat supports.

The clamps shown in Figs. 1 to 13 inclusive and described but not claimed herein form the subject matter of my copending application filed June 12, 1943, Serial No. 490,563. g

It is evident that various changes may be resorted to in the construction, form and arrangement of the several parts without departing from the spirit and scope of my invention, and hence I do not intend to be limited to the particular embodiments herein shown and described, but

what I claim is:

1. In a plate clamp adapted to be moved along I a grooved support into engagement with, an edge of a printing plate, a hook, a nut slidable in said grooved support and a clamp screw passing through the hook into threaded engagement with the nut, said hook and nut having curved coacting surfaces concentric with the clamp screw for preventing the hook from exerting side strain on the screw when the nut is subjected to endwise force and also to permit the hook to be properly seated against the edge of the printing plate.

2. In a plate clamp adapted to be moved along a grooved support into engagement with an edge of a printing plate, a hook, a nut slidable in said grooved support and a clamp screw passing through the hook into threaded engagement with the nut, said hook having a circular element concentric with the clamp screw, and said nut having a circular recess for receiving said circular element for permitting the rotative adjustment of the hook and preventing the hook from exerting side strain on the screw when the nut is subjected to endwise force.

' screw passing through the hook and guide member into threaded engagement with the nut,said guide member and nut having curved coacting surfaces concentric with the clamp screwand arranged to prevent the hook from exerting side strain on the screw when the nut is subjected to endwise force and also to permit the hook to be properly seated against the edge of the printing plate.

4. In a plate clamp adapted to be moved along a grooved support into engagement with an edge of a printing plate, a hook provided with a guide member slidable in a grooveof 'said support, a nut also slidable in said groove and a clamp screw passing through the hook and guide member into threaded engagement with the nut, said .nut having a recess for receiving the guide member and also having a curved shoulder concentric with the clamp screw and which coacts with the guide member to prevent the hook from exerting side strain on the screw when the nut is subjected to endwise force and also to permit the hook to be properly seated against the edge of the printing plate.

5. In a plate clamp adapted to be moved along a grooved support into engagement with an edge of a printing plate, a hook provided with a guide.-

member slidable in a groove of said support, a' nut also slidable in said groove, and a clamp. screw passing through the hook and guide mem ber into threaded engagement with the nut, said guide member and nut having circular coacting surfaces concentric with the clamp screw for rotatively mounting the hook on the nut and for preventing the hook from exerting a side strain on the clamp screw when the nut is subjected to endwise force.

6. In a plate clamp adapted to be moved along a grooved support into engagement with an edge when the nut is subjected to endwise force and also to permit the hook to be properly seated against the edge of the printing plate.

7. In a plate clamp adapted to be moved along a grooved support into engagement with one edge of a printing plate, a plate hook provided with a circular guide member, a nut having a circular recess for snugly housing the circular guide member, and a clamp screw passing through said hook and centrally through said guide member and recess into threaded engagement with the nut, the circular coacting side Walls of the guide member and recess serving to rotatively mount the hook on the nut and to prevent the hook from exerting a side strain on the clamp screw when the nut is subjected to endwise force.

HOWARD M. BARBER. 

